My Lib Dem colleagues and I will not stand by and watch private investors reap all of the benefits once the banks are taken off intensive care.

An employee of the Royal Bank of Scotland walks inside the company headquarters at Gogarburn in Edinburgh. Photograph: Getty Images.

Despite its importance to our economy, the world of finance has never elicited such a visceral repulsion from the public. This feeling can be summed up in three words: banks, bankers, bonuses.

The effects of the financial crisis of 2008-9 are still felt throughout British society and around the world. While the stewardship of the coalition government means interest rates remain low, the cost of bailing out the banks (an eye-watering £66bn) means that few Britons are immune from the deficit reduction plan necessary to return the nation’s books to good health. With this in mind, my Liberal Democrat colleagues and I strongly favour giving the public something back for the pain visited on them by the financial sector’s actions (we hope they will punish Labour politicians in 2015 for their own role in not saving for a rainy day). In a 2011 Centre Forum paper, in conjunction with Portman Capital, I proposed a public distribution of the government-owned RBS and Lloyds shares with a floor price built into the sale, meaning the government would re-coup its original investment in the two banks with the public gaining in the increase in the share price. This idea will sound familiar as several groups have since proposed similar ideas, most recently Policy Exchange.

How does the floor price work?

For illustrative purposes only, let us assume that the price of the share is 1000p on the day of distribution with the floor set at 850p. When an investor sells, the Treasury receives the first 850p and also Capital Gains Tax on the difference between the floor and the sale price. The investor receives the balance. In our example, if the investor were to sell immediately at 1000p she would receive 123p, with the Treasury receiving 877p. However, if the investor waited and sold at 1500p his return would rise to 533p per share, with the Treasury receiving 967p. When you sell your shares, the "floor price" is deducted from the sale price, with the public receiving the difference. The floor price will be based on the prevailing market price, but will be at least the 51p per share we paid for RBS and the 74p per share we paid for Lloyds.

Why a conventional privatisation should be rejected

A "share overhang" is when the market expects a large sale from one seller, the situation we would find ourselves in if a normal privatisation is pursued. Worse, as the government owns such a large proportion of the banks, the market is unable to absorb all of the shares at once, requiring the staging of sales over a number of years. Thus, the shares would have to be sold below market price, with the initial sales being the most heavily discounted, destroying value for British taxpayers. This happened when the US government sold its shares in GM Motors, with the first tranche of shares selling for $11 less than the break-even price to recoup its original investment.

A YouGov poll shortly after my policy was announced found that the majority of the public, across all political parties, supported my idea. The list of supporters has grown since then to include MPs from all sides and think-tanks from across the political spectrum (most recently the Tory-facing Policy Exchange). The Chancellor should now join the list and announce that the coalition’s intention is to begin a public distribution once a sale of the shares is feasible. The Lloyds share price is sufficient enough to be considered for a sale in the near future, though RBS, despite Stephen Hester’s suggestion that it could be privatised by as early as next year, needs more time to regain strength before we will be confident of recouping our bailout cost from its share price.

The issue of what to do with the government-owned shares in RBS and Lloyds will dominate the next couple of years of the coalition, leading up to the 2015 election. I hope that this debate will focus on the nuances of a public share distribution (who should be eligible? how will voting rights be awarded?), rather than criticism of a typical privatisation whereby rich individuals profit from institutions saved by the taxpayer. My Lib Dem colleagues and I will not stand by and watch private investors reap all of the benefits once the banks are taken off intensive care; the public must get their share.

Stephen Williams is MP for Bristol West and co-chair of the Liberal Democrat Treasury Parliamentary Policy Committee